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How might climate change affect my region? Climate change in the West Coast

The climate of the West Coast is greatly dependent on its exposure to weather systems from the Tasman Sea and the lie of the Southern Alps, with heavy rainfall, mild summers and cool winters.

A change in our climate as a result of global warming and other influences means we need to think about how we are going to plan for and manage the projected impacts of climate change in the West Coast and New Zealand. But we also need to take appropriate action to reduce our share of greenhouse gas emissions responsible for global warming and climate change impacts.

Some of the predicted impacts of a moderate rate of climate change for the West Coast include changes in average temperature, sea level rise and rainfall patterns. In general, the West Coast, like much of the west coast of New Zealand is likely to be warmer and wetter.

Climate scientists estimate that the West Coast's temperature could be up to 2.5°C warmer over the next 70- 100 years. This compares to a temperature increase in New Zealand during last century of about 0.7°C. To put this in perspective, the 1997/98 summer, which many New Zealanders remember as particularly long, hot and dry, was only about 0.9°C above New Zealand 's average for the 1990s.

The West Coast could be up to 25% wetter with more varied rainfall patterns and flooding could become up to four times as frequent by 2070.

The effects of climate change may bring significant costs to the community.

If extreme weather events become more frequent or severe, the costs and damages associated with them are also likely to increase. The cost of dealing with stock losses, replacing or repairing damaged roads, bridges, houses and stormwater drains, and dealing with increased soil erosion and loss of soil nutrients can be formidable. Recent extreme weather events such as the Marlborough and Canterbury droughts, Cyclone Bola, the "weather bomb" in the Waikato/Coromandel area, and coastal flooding during the Waitangi Day storm, have shown how vulnerable our society and economy is to the weather and climate.

There are likely to be benefits and opportunities from a change in climate too. Farmers could benefit from better crop growing conditions and faster growth of pasture but more use of fertiliser may be needed.

However, if the rate and magnitude of climate change is not slowed down, that is, if we don't reduce greenhouse gas emissions, any beneficial effects of climate change are expected to diminish and the adverse effects and long-term risks expected to increase.

The West Coast's climate

The climate of this region is greatly dependent on its exposure to weather systems from the Tasman Sea and the lie of the Southern Alps to the east. Although mean annual rainfall is very high, dry spells do occur, especially in late summer and during winter. Heavy rainfall occurs from the northwest. Summers are mild. Typical summer daytime maximum air temperatures range from 17°C to 22°C and seldom exceed 25°C. Winter days often start with frost. Typical winter daytime maximum air temperatures range from 10°C to 14°C. North northeast winds prevail along the coast in Westport and Hokitika while southwesterlies prevail in coastal areas further south. Sea breezes can occur on warm summer days.

Last updated: 20 March 2008